escape manager

uxie/escape.py

@@ -0,0 +1,38 @@
+import time
+import weakref
+from bisect import bisect
+
+class Escapable(object):
+    def __init__(self, callback, *args):
+        self.callback = callback
+        self.args = map(weakref.ref, args)
+
+    def cancel(self):
+        args = [a() for a in self.args]
+        self.callback(*args)
+
+    def is_active(self):
+        args = [a() for a in self.args]
+        return not any(a is None for a in args)
+
+
+class Manager(object):
+    def __init__(self):
+        self.escape_stack = []
+
+    def push(self, obj, priority=None):
+        if priority is None:
+            priority = 0
+
+        item = (-priority, time.time(), obj)
+        self.escape_stack.insert(bisect(self.escape_stack, item), item)
+        return obj
+
+    def process(self):
+        while self.escape_stack:
+            _, _, obj = self.escape_stack.pop()
+            if obj.is_active():
+                obj.cancel()
+                return False
+
+        return True